Glaucoma is a disease where the nerve fibers that form the optic nerve degenerate over time and cause loss of sight corresponding to the areas of the retina from which the nerve fibers transmit the photopic stimulation. Elevated intraocular pressure (IOP) is the primary risk factor for degeneration of these nerve fibers and reduction of the interocular pressure is the primary goal of treatment to prevent further loss of optic nerve tissue and the associated visual loss.
Vision loss from glaucoma can be delayed or prevented in most patients by lowering the intraocular pressure. This may be accomplished by using topical medications, laser treatment or trabeculectomy to increase an outflow of aqueous humor from the anterior chamber of the eye. When these methods fail to control intraocular pressure, ophthalmic surgeons may use aqueous drainage devices or “glaucoma shunts” to facilitate movement of aqueous humor from the anterior chamber to outside the eye and thus reduce high levels of intraocular pressure. Currently, these devices are used as a secondary intervention because some believe they have a relatively high complication and failure rate.